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The authorship of each patch in a series
by Fabio M. De Francesco Sept. 2, 2021

Sept. 2, 2021

Hi all, Another developer and I collaborated to design and write a series of four patches. Of course, we will both use the "Co-developed-by" and "Signed-off- by" tags on each of the four works that make up the series. However, there is a small problem that we would like to solve. Git-log only displays a single name preceded by "Author:", so the reader of "git log -- pretty = short" will only be shown one of our names. We would like git-log to show one name after "Author:" in 1/4 and 4/4 and the other name in 2/4 and 3/4. This arbitrary breakdown is based on the fact that approximately 80% -90% of the lines of code from the first patch group were actually written by one of the two co-developers and approximately 80% -90% of the second patch group was written by the other. I guess Git will label anyone who submits the whole series as "Author"; works like this or am I wrong? If so, I guess if my friend sends patches 0/4, 1/4 and 4/4 then I should find a way to send 2/4 and 3/4 somehow that makes it clear to the maintainer, the tool that uses to apply the series, and the reviewers, which also 2/4 and 3/4 belong to the same series as 0/4, 1/4 and 4/4. How can we achieve this? Thanks, Fabio

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how do you find the subsystem of a file?
by daniel watson Sept. 1, 2021

Sept. 1, 2021

i wrote a patch that got rejected because it did not apply cleanly to the tree of greg kh https://lkml.org/lkml/2021/8/18/304 the file i modified is drivers/staging/rtl8723bs/include/rtl8192c_recv.h get_maintainer.pl gave me the list of emails to send the patch to, and i used it for that purpose. the file Documentation/process/submitting-patches.rst says to see the T: entry for the subsystem in MAINTAINERS to find the right tree to base the patch on. i tried searching through MAINTAINERS and found that there are a few subsystems that start with RTL8*. greg kh is listed a few times in MAINTAINERS, so i'm not able to find the exact tree to start with by looking for the maintainer. is there a systematic way of finding the subsystem, given a file? in addition, how do i know what branch to use? the T: entries have a repo, but not a branch name. thanks! :wq, danny

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MODULE_SUPPORTED_DEVICE macro existed in the Kernel 5.9.16, but got removed
by Adverg Ebashinskii Sept. 1, 2021

Sept. 1, 2021

I recently tried to compile my driver developed for the Kernel 5.9.16 using the latest upstream version checked out from git and figured out that there is no more MODULE_SUPPORTED_DEVICE macro. Could you please give a hint where to look at for the information on why it was removed? -- Regards, Adverg Ebashinskii

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Device doesnt show up on Ble Scanner - gatt-service example in tools folder as per Documentation(doc)
by Raul Piper Aug. 31, 2021

Aug. 31, 2021

Hello, I tried cross compiling the bluez and ported it to my linux platform.I think i have done it correctly as I am able to launch the gatt-service example successfully but i am not able to view it on the Smartphone app - blescanner or light blue. Below are the logs : =============================================== ./gatt-service gatt-service unique name: :1.18 Registered service: /service1 Registered service: /service2 Registered service: /service3 Get Primary: True Get UUID: 00001802-0000-1000-8000-00805f9b34fb Exist Includes: 00001802-0000-1000-8000-00805f9b34fb Get Includes: 00001802-0000-1000-8000-00805f9b34fb Includes path: /service3 Get Includes: /service2 Characteristic(00002a06-0000-1000-8000-00805f9b34fb): Get("Value") Descriptor(8260c653-1a54-426b-9e36-e84c238bc669): Get("Value") Get Primary: True Get UUID: A00C Exist Includes: A00C Characteristic(00002c07-0000-1000-8000-00805f9b34fb): Get("Value") Descriptor(FFFF): Get("Value") Get Primary: True Get UUID: A00D Exist Includes: A00D Characteristic(00002b06-0000-1000-8000-00805f9b34fb): Get("Value") Descriptor(0260c653-1a54-426b-9e36-e84c238bc669): Get("Value") I also tried to run the python example inside test/example-gatt-server but again I am not able to view the device name. Below are the logs : ======================================= python3 example-gatt-server example-gatt-server:395: PyGIDeprecationWarning: GObject.timeout_add is deprecated; use GLib.timeout_add instead GObject.timeout_add(5000, self.drain_battery) example-gatt-server:652: PyGIDeprecationWarning: GObject.MainLoop is deprecated; use GLib.MainLoop instead mainloop = GObject.MainLoop() Registering GATT application... GetManagedObjects GATT application registered I even opened the btmon on a different tab but still I am not able to see anything on that. Is there any other application we have to run? Has any one ran it successfully and able to view/connect and see all the 3 services it is advertising. Please advise / ask for any further information , I will provide. Thanks in advance ! Regards, R

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how to properly use BUILD_BUG_ON_MSG ?
by jim.cromie＠gmail.com Aug. 30, 2021

Aug. 30, 2021

so I got this macro which depends upon config choices to work, Id like to have alt-config versions which throw some obvious error. like this: #elif (defined(CONFIG_DYNAMIC_DEBUG_CORE) && !defined(DYNAMIC_DEBUG_MODULE)) #define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ BUILD_BUG_ON_MSG(1, "you need -DDYNAMIC_DEBUG_MODULE in compile") #else ... is that more or less the expected usage ? the error messages seem less clear than Id like, leading me to suspect poor usage, or a better way to do it. /home/jimc/projects/lx/wk-next/include/linux/compiler_types.h:310:11: error: expected identifier or ‘(’ before ‘while’ 310 | } while (0) | ^~~~~ /home/jimc/projects/lx/wk-next/include/linux/compiler_types.h:316:9: note: in expansion of macro ‘__compiletime_assert’ 316 | __compiletime_assert(condition, msg, prefix, suffix) | ^~~~~~~~~~~~~~~~~~~~ /home/jimc/projects/lx/wk-next/include/linux/compiler_types.h:328:9: note: in expansion of macro ‘_compiletime_assert’ 328 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) | ^~~~~~~~~~~~~~~~~~~ /home/jimc/projects/lx/wk-next/include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’ 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | ^~~~~~~~~~~~~~~~~~ /home/jimc/projects/lx/wk-next/include/linux/dynamic_debug.h:283:9: note: in expansion of macro ‘BUILD_BUG_ON_MSG’ 283 | BUILD_BUG_ON_MSG(1, "you need -DDYNAMIC_DEBUG_MODULE in compile") | ^~~~~~~~~~~~~~~~ /home/jimc/projects/lx/wk-next/drivers/gpu/drm/drm_print.c:60:1: note: in expansion of macro ‘DEFINE_DYNAMIC_DEBUG_CATEGORIES’ 60 | DEFINE_DYNAMIC_DEBUG_CATEGORIES(debug, __drm_debug, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #if defined(CONFIG_DYNAMIC_DEBUG) || \ (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) /** * DEFINE_DYNAMIC_DEBUG_CATEGORIES() - bitmap control of categorized prdbgs * @fsname: parameter basename under /sys * @var: C-identifier holding bitmap * @_desc: string summarizing the controls provided * @...: list of struct dyndbg_bitdesc initializations * * Intended for modules with substantial use of "categorized" prdbgs * (those with some systematic prefix in the format string), this lets * modules (using dyndbg) control those prdbg groups according to * their prefixes, and map them to bits 0-N of a sysfs control point. * The @bits... identifies the prefixes to be used by dyndbg to * select and alter those categorized prdbgs, order defines bitpos. */ #define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, _var, _desc, ...) \ MODULE_PARM_DESC(fsname, _desc); \ static struct dyndbg_bitmap_param ddcats_##_var = \ { .bits = &_var, .map = { __VA_ARGS__, { .prefix = NULL }}}; \ module_param_cb(fsname, &param_ops_dyndbg, &ddcats_##_var, 0644) #define _DD_cat_(pfx) { .prefix = pfx, .help = "help for " pfx } #define _DD_cat_help_(pfx) "\t " pfx "\t- help for " pfx "\n" extern const struct kernel_param_ops param_ops_dyndbg; #elif (defined(CONFIG_DYNAMIC_DEBUG_CORE) && !defined(DYNAMIC_DEBUG_MODULE)) #define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ BUILD_BUG_ON_MSG(1, "you need -DDYNAMIC_DEBUG_MODULE in compile") #else #define DEFINE_DYNAMIC_DEBUG_CATEGORIES(fsname, var, bitmap_desc, ...) \ BUILD_BUG_ON_MSG(1, "DYNAMIC_DEBUG support required to use this macro: " #var) #define _DD_cat_(pfx) #define _DD_cat_help_(pfx) #endif #endif

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Re: Kernel 4.14: Using dm-verity with squashfs rootfs - mounting issue
by Pintu Agarwal Aug. 30, 2021

Aug. 30, 2021

On Wed, 21 Jul 2021 at 22:40, Mikulas Patocka <mpatocka(a)redhat.com> wrote: > > > > > > Try to set up dm-verity with block size 512 bytes. > > > > > > I don't know what block size does squashfs use, but if the filesystem > > > block size is smaller than dm-verity block size, it doesn't work. > > > > > Okay thank you so much for this clue, > > It seems we are using 65536 as the squashfs block size: > > 65536 is the compression block size - it is unrelated to I/O block size. > > There's a config option SQUASHFS_4K_DEVBLK_SIZE. The documentation says > that it uses by default 1K block size and if you enable this option, it > uses 4K block size. > Okay it seems this config is set in our case: CONFIG_SQUASHFS_4K_DEVBLK_SIZE=y So, with this the squashfs and dm-verity block size exactly matches (4K) > So, try to set it. Or try to reduce dm-verity block size down to 1K. > Okay we are trying this. Thank you so much!! Regards, Pintu

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Get notification when a block device is mounted.
by Douglas Su Aug. 30, 2021

Aug. 30, 2021

Hi, all: I want to get notified when a block device is mounted, and after some google searches, it seems a syscall named "mount_notified()" existed before but was removed in the latest kernel. For the latest kernel, is there any system call or other mechanisms cater this purpose? Thanks

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USB/HID: Device with multiple interfaces
by José Expósito Aug. 29, 2021

Aug. 29, 2021

Hi all, I'm trying to solve an issue with a mouse that only reports battery over Bluetooth. I hope you can help me. When connected over Bluetooth, the mouse registers one HID descriptor containing both mouse and power device collections. However, when it's connected over USB, I can see using lsusb that 3 interfaces are available and, unlike with Bluethoot, the HID descriptors containing mouse and power device are in different interfaces. The battery percentage is not reported in this case. So far I've been able to get the battery percentage in the driver by manually calling devm_power_supply_register and submitting an URB. My question is: since the HID descriptors with the power device collection is present but in a different interface, is there a way to associate both interfaces to the same physical device and get the battery percentage automatically? Thank you very much in advance, Jose

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Update of kernelnewbies.org/FirstKernelPatch required
by Philipp Hortmann Aug. 29, 2021

Aug. 29, 2021

Hi, I am just following the "FirstKernelPatch" instructions and found out that yahoo as email account does not work anymore. Reason is that the Security Setting "Allow apps that use less secure sign-in" does not exist anymore. For gmail it is required to activate the option "Allow apps that use less secure sign-in" to be able to conduct the following steps of the instructions. This hint is missing. A proposal from "greg at kroah.com Sun Dec 27 03:50:21 2020" proposes to use fastmail.fm fastmail.fm is not for free and also not mentioned in the "FirstKernelPatch" instructions. Please do not let all newbies fall into this trap. Please provide me a login or edit yourself. Thanks for your support. Bye Philipp

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Contributing to drivers/staging area
by Len Baker Aug. 27, 2021

Aug. 27, 2021

Hi Greg, I am a kernel newbie in the path to find an area where to contribute on. I have sent some patches before (simple ones) but I would like to find some driver to contribute on and if possible mantain in the future. Due to the big amount of drivers in staging, and my lack of experience and specific hardware: Are there any driver in the staging area that not requires specific hardware? I have only access to an old laptop with 4 processors: vendor_id : GenuineIntel cpu family : 6 model : 37 model name : Intel(R) Core(TM) i3 CPU M 370 @ 2.40GHz Can I find a driver to contribute on with my machine requirements? If yes, any advise to select one would be greatly appreciated. I would like to improve the driver until get it out from staging ;) And then maintain it. Another option for me if there are no drivers would be create one from zero. But I don't have any idea of useful driver. Any advise and ideas here would be also great appreciated. Thanks in advance. Regards, Len

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